You will never see the provincial sides return, unfortunately. Lets face it, the AirNZ Cup is the new club rugby.
I would like to see up to another four to six teams - USA, Japan, Argentina, Islands, etc - and a two conference system of two divisions of nine or ten teams playing home and away. A finals series between, say, the top five qualifiers (first and second from each conference plus the third placed team from either conference with the highest points) like they do in the NRL would add lots of interest to the final series.
I would then play the Air NZ Cup at the same time as the Super 18/20 as a sort of local N.Z. reserve grade competition where it is clear you are a feeder team and you play on the way up to impress the big time pro-league, or as a punishment, or even as part of a gradual retirement from the game for players past their best who may still get a few extra years passing on skills for a reduced salary...
By my calculation, that would reduce the rugby season to 22-24 weeks (if you give teams bye weeks) and leave plenty of windows for international games.
Club, touch and school rugby could then be split away from the NZRU professional administration into a completely amateur organisation, and the Ranfurly Shield would become the premier trophy for club teams played for in a separate tournament for regional club competition winners.